The present invention relates generally to CMOS image sensors, and more particularly, to a single chip image sensor having integrated therewith pattern recognition circuitry.
CMOS image sensors are used in a variety of applications. From optical mice, to PC cameras, to security cameras, CMOS image sensors have proven their ability to supplant CCD technology. With their lower cost and lower power consumption, CMOS image sensors have become an important alternative to CCD""S.
In many applications, the image captured by the image sensor is not simply output for viewing. Instead, the image sensor data is used for other purposes, such as to detect movement in an optical mouse, or to detect movement in objects. As one example, image sensors used in toys or machine vision devices are often used to detect movement. The image sensors also are often used to identify shapes or objects in the image field.
For these applications, significant signal processing on the images must be performed. Typically, the signal processing is performed on a separate chip by a conventional digital signal processor, a microprocessor, or other logic device, such as a field programmable gate array (FPGA) or programmable logic device (PLD).
However, the use of additional chips for signal processing is expensive. For example, a large FPGA with millions of gates may cost upwards of $10 per unit. For pattern recognition applications, it is not necessary to use a large FPGA. Moreover, smaller gate count FPGA""s are not readily available. Therefore, a standard high processing power FPGA is used, with much of the processing power of the FPGA is wasted.